α-Fe₂O₃-supported Co₃O₄ nanoparticles to construct highly active interfacial oxygen vacancies for ozone decomposition

Ozone pollution has become one of the most concerned environmental issue. Developing low-cost and efficient catalysts is a promising alternative for ozone decomposition. This work presents a creative strategy that using α-Fe₂O₃-supported Co₃O₄ nanoparticles for constructing interfacial oxygen vacancies (Vo) to remove ozone. The efficiency of Co₃O₄/α-Fe₂O₃ was superior to that of pure α-Fe₂O₃ by nearly two times for 200-ppm ozone removal after 6-h reaction at 25 °C, which is ascribed to the highly active interfacial Vo. X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy suggest that the Fe³⁺-Vo-Co²⁺ was formed when Co₃O₄ was loaded in α-Fe₂O₃. Furthermore, the density functional theory (DFT) calculations reveal the desorption and electron transfer ability of intermediate peroxide (O₂^2-) on Fe³⁺-Vo-Co²⁺ are higher than the Vo from other regions. In situ diffuse reflectance Fourier transform (DRIFT) spectroscopy also demonstrate the higher conversion rate of O₂^2- on Co₃O₄/α-Fe₂O₃. Base on the intermediates detected, we propose a recycle mechanism of interfacial Vo for ozone removal: O₂^2- is quickly converted to O₂^- and transformed into O₂ on interfacial Vo. Moreover, O₂-temperature-programmed desorption (TPD), H₂-temperature-programmed reduction (TPR), and electrochemical impedance spectroscopy (EIS) reveal that the oxygen mobility, reducibility, and conductivity of Co₃O₄/α-Fe₂O₃ are greatly superior to those of α-Fe₂O₃, which is contributed to the conversion of O₂^2-. Consequently, our proposed strategy effectively enhances the activity and stability of the bimetallic transition oxides for ozone decomposition.